Blasting methods and materials



Oct. 11, 1960 J. E LAMBERT ETAL BLASTING METHODS AND MATERIALS 6Sheets-Sheet 1 Filed May 17, 1956 IN l/E/VTOR JAMES EDWARDLAMBEM IDWALOWE/V LEW/5 ATTORNE S FIG. 2.

Oct. 11, 1960 J. E. LAMBERT ETAL 2,955,534

BLASTING METHODS AND MATERIALS 6 Sheets-Sheet 2 Filed May 17. 1956VNVEIVTOR JAMES EDWARD LAMBERT IDWAL OWE/V LEW/S B W K044i; M

Oct. 11, 1960 J. E. LAMBERT ETAL 2,

BLASTING METHODS AND MATERIALS Filed May l7, 1956 6 Sheets-Sheet 3INVENTOR JAMES 5mm RDLAMBERT lDWAL ows/v LEW/5 FIGS BJ MMMJZ ATTOR/VE'KY Oct. 11, 1960 .1. E, LAMBERT ETAL 2,955,534

BLASTING METHODS AND MATERIALS Filed May 17, 1956 6 Sheets-Sheet 4ATTOR/VEKg Oct. 11, 1960 J. E. LAMBERT ETAL 2,955,534

BLASTING METHODS AND MATERIALS 6 Sheets-Sheet 5 Filed May 17, 1956I/VVE/VTQR JAMESEDWARD LAMBERT IDWAL OWE/V LEW/S [MW A TTOR/VE Y S Oct11, 1960 J. E. LAMBERT EI'AL 2,955,534

BLASTING METHODS AND MATERIALS 6 Sheets-Sheet 6 Filed May 17. 1956INVENTOR RD LAMBERT LEW/5 uA MES EDWA IDWAL OWE/V M, 911417 ATTORNEYJ'FIG. IO J BLASTING METHODS AND MATERIALS James Edward Lambert and IdwalOwen Lewis, Ardrossan, Scotland, assiguors to Imperial ChemicalIndustries Limited, London, England, a corporation of Great BritainFiled May 17, 1956, Ser. No. 585,431

Claims priority, application Great Britain July 27, 1955 3 Claims...(Cl. 102-43) The present invention is concerned with a new method ofwinning coal, rock, metal and the like in opencast working, quarrying orstrip mining with blasting explosive compositions and more particularlywith blasting explosive compositions containing a substantial proportionof ammonium nitrate and to apparatus therefor.

Hitherto it has been the practice to manufacture a blasting explosivecomposition and to cartridge or otherwise package it in a factory, totransport the cartridges or packages to the blasting site and to loadthe borehole with the explosive composition either in its waxed papercartridge casing or other container or to empty the explosivecomposition out of its containers into the borehole. This procedureentails the observing of statutory regulations for the production,transport and handling of explosive compositions. Since ammonium nitratecan be handled and transported otherwise than as an explosive therewould be economic and safety advantages if the mixing of ammoniumnitrate and the other ingredients forming explosive compositionscontaining a substantial proportion of ammonium nitrate were delayed aslong as possible, for example if the mixing were done in a building atthe blasting site or better in a borehole.

According to the present invention the method of winning coal, rock,metal and the like in opencast working, quarrying or strip miningcomprises forming in a substantially vertical bore hole an ammoniumnitrate blasting explosive composition by introducing into itconcurrently and at a predetermined rate at least one stream of ammoniumnitrate and at least one stream in solid form containing the otheringredients of the blasting explosive composition so that the streamsco-mingle during their descent in the borehole.

It is often desirable that said streams should only comingle belowground level.

In carrying out the method of the invention in accordance with oneembodiment thereof the particles forming said streams can havesuperimposed on their gravitational descent at least one non-verticalcomponent of motion for example by means of stationary baffles or bymeans of rotating bafiies or paddles mounted on a suitable rotatingmember. Proceeding in this way often increases the efliciency of theco-mingling.

In accordance with a further embodiment of the invention protection ofthe blasting explosive composition containing the water-soluble ammoniumnitrate from moisture in wet boreholes can be achieved by inserting intothe borehole, prior to the introduction of said streams, a tube of anysuitable waterproof material sealed at its lower end, which if necessarymay be protected against mechanical damage on the rough side of theborehole by the use of a borehole liner interposed between the surfaceof the borehole and the waterproof tube which may be for example ofwaterproof laminated paper or cardboard. If desired the container may beclosed at its upper end after being loaded.

Apparatus for carrying out the method of the inven- Dion comprises atube having lixed to its internal surface 2,955,534 Patented Oct. 11,1960 a plurality of batfie plates so positioned that with the axis ofthe tube substantially vertical powdered or granular material pouredinto the top of the tube will be deflected more than once and alsohaving attached to the end which is to serve as the top of the tube atleast two branched conduits.

At least one of said conduits may contain a screw conveyor or othermeans for conveying powdered or granular material. Alternatively atleast one of said conduits may be connected to a source of compressedair.

The invention also includes forming ammonium nitrate blasting explosivesby a method which comprises introducing into a substantially verticalborehole concurrently and at a predetermined rate at least one stream ofammonium nitrate and at least one stream in solid form containing theother ingredients of the blasting explosive composition so that thestreams co-mingle during their descent in the borehole.

By way of example the invention will be described with reference to thediagrammatic drawings accompanying the specification.

Figure l is a longitudinal axial section through one form of apparatusaccording to the invention and Figure 2 is a section on the line A-Aviewed in the direction of the arrow X. In Figures 1 and 2, 1, 1' arehoppers, 2, 2' are screw conveyors situated co-axially in theirrespective conduits 3, 3 which lead to tube 4. Tube 4 contains fourinternal bafiles 5.

One of the hoppers 1, 1 contains for instance that quantity of ammoniumnitrate and the other hopper for instance that quantity of thecomplementary ingredient or ingredients of a particular ammonium nitrateblasting explosive composition that about lbs. of the explosivecompositions can be produced in a borehole. The two screw conveyorspindles 2, 2 may be manual or power operated. Tube 4 is about 5 feetlong and 5 inches internal diameter and can be inserted into a ver ticalborehole approximately 30 feet deep and 6.5 inches diameter.

Another form of apparatus according to the invention is illustrated inFigures 3 and 4 in longitudinal axial section and in section on line BBin the direction of arrow Y respectively. This apparatus has in additionto the features illustrated in Figures 1 and 2 a vertical stirrer 6capable of continuous rotation (which may be adapted either for manualoperation as shown or for power operation), to assist further the mixingof the ammonium nitrate and the complementary ingredients of theblasting explosive composition in the vertical tube.

In yet another form of apparatus according to the in vention illustratedin Figure 5 a metering device for example a screw conveyor asillustrated is provided for the admission of ammonium nitrate containedin a hopper. The complementary ingredients of the ammonium nitrateblasting explosive composition are added manually in the requiredproportion from a container into a wide-mouthed conduit leading into thevertical tube.

Figure 6 illustrates a vertical borehole ready for blasting after havingbeen loaded according to the invention in which 7 is the completeexplosive composition, 8 is a primer cartridge of for example a gelatineexplosive such as 5 in. x 5 lb. cartridge of Opencast Gelignite, 9 is alength of detonating fuse and 10 is earth stemmed tightly into theborehole.

Figure 7 illustrates a vertical borehole being loaded with an explosivecomposition employing apparatus according to one form of the invention.

Figure 8 illustrates a vertical borehole loaded according to theinvention and differs from Figure 6 in that a waterproof tube 11 isemployed to protect the explosive composition from moisture in theborehole.

Figures 9 and 10 illustrate a vertical borehole being Example 1 ANitroglycerine 20% (by weight).

Coarse sawdust 80% (by g B Ammonium nitrate.

By combining A and B in the ratio of 1 part by weight to 5 parts byweight an explosive composition is produced which has a power of 80%blasting gelatine when measured on the ballistic mortar and whichdetonates at a velocity of 3,000 metres per second in a 5" diametercolumn when initiated by a 2 lb. gelignite primer.

Example 2 C Trinitrotoluene 64% (by weight).

Ground anthracite 36% (by weight) D Ammonium nitrate.

By combining C and D in the ratio of 1 part by weight to 7 parts byweight an explosive composition is produced which has a power of 83%blasting gelatine as measured on the ballistic mortar and whichdetonates at a velocity of 3,500 metres per second in a 5" diametercolumn when initiated by a 2 lb. gelatine primer.

Example 3 E Trinitrotoluene 38% (by weight).

f Ground anthracite 62% (by weight). F Ammonium nitrate.

By combining E and F in the approximate ratio of 1 part by weight to 9parts by weight an explosive composition is produced which has a powerof 81% blasting gelatine as measured on the ballistic mortar and whichdetonates ata velocity of 3,000 metres per second in a 5" diametercolumn when initiated by a 2 lb. gelatine primer.

Example 4 G Sawdust 50% (by weight).

Parafiin oil 50% (by weight). H Ammonium nitrate.

By combining G and H in the ratio of 1 part by weight to 12 parts byweight an explosive composition is produced which has a power of 80%blasting gelatine as measured on the ballistic mortar and whichdetonates at a velocity of 3,500 metres per second in a 5" diametercolumn when initiated by a lb. gelatine primer.

Example 5 I Ground anthracite. J Ammonium nitrate.

By combining I and I in the ratio of 1 part by weight to 13 parts byweight an explosive composition is produced which has a power of 76%blasting gelatine as measured on the ballistic mortar and whichdetonates at a velocity of 2,500 metres per second in a 5" diametercolumn when initiated by a 4 lb. gelatine explosive primer.

What we claim is:

1. A method of loading boreholes for the purpose of winning coal, rock,metal and the like in opencast working, quarrying or strip mining whichcomprises forming in a substantially vertical borehole an ammoniumnitrate blasting explosive composition by introducing into itconcurrently and at a predetermined rate at least one stream consistingof dry solid particles of ammonium nitrate and at least one stream ofdry solid particles containing the other ingredients of the blastingexplosive composition so that the streams co-mingle during their descentin the borehole.

2. A method as claimed in claim 1 wherein said streams only co-minglebelow ground level.

3. A method as claimed in claim 1 wherein the particles forming saidstream have superimposed on their gravitational descent at least onenon-vertical component of motion and wherein said non-vertical componentof motion is created by causing said streams to impinge upon a rotatingupwardly converging conical surface within said borehole during theirdescent.

References Cited in the file of this patent UNITED STATES PATENTS2,083,706 Harris June 15, 1937 2,312,752 Cook -Mar. 2, 1943 2,345,554Burdett Apr. 4, 1944 2,364,415 Arnold et a1. Dec. 5, 1944 2,504,611Zandmer Apr. 18, 1950 2,704,514 Barlow et al Mar. 22, 1955 2,745,346Aitchison et a1. May 15, 1956 2,836,484 Streng et a1 May 27, 19582,903,969 Kolbe Sept. 15, 1959 FOREIGN PATENTS 44,422 Germany Aug. 29,1888 528,941 Great Britain Nov. 11, 1940 581,849 Great Britain Oct. 28,1946 725,371 Great Britain Mar. 2, 1955

